The present invention relates to a controller for an interior system for use in an automotive vehicle.
A controller for an interior system for use in an automotive vehicle is now in practical use, which operates an air bag, a seat belt pretensioner, etc. for absorbing an impact when an acceleration sensor detects, upon frontal collision of the automotive vehicle, an impact greater than a predetermined value (see, for example, a Manual of NISSAN New Model Cars No. Y32-1, published in Jun., 1991).
Referring to FIG. 4, there is shown a block diagram illustrating such known interior system controller 1. An electronic acceleration sensor part 11 comprises, for example, a cantilevered piezoelectric element which is deformed when undergoing acceleration in a predetermined direction so as to output to an amplifier filter part 12 a voltage 101 in response to a deformation amount thereof. The amplifier filter part 12 amplifies the input voltage 101 to eliminate a needless frequency, and outputs an acceleration signal 102 to a signal processing part 13. As disclosed, for example, in JP-A 63-503531, the signal processing part 13 comprises a subtracter D, an integrator I, and a threshold value generator S. The subtracter D subtracts a threshold value of the threshold value generator S from the acceleration signal 102, whereas the integrator I integrates the acceleration signal 102 after subtraction processing. That is, the signal processing part 13 integrates the acceleration signal 102 greater than the threshold value to output same to an operation decision part 14. When an integration signal 103 out of the signal processing part 13 becomes a predetermined value, the operation decision part 14 outputs an output indicative signal 104 to an output part 15 so as to operate an operation part 3 for an interior system such as an air bag, a seat belt pretensioner, etc. in a manner similar to, for example, a trigger threshold value switch A as shown in JP-A 63-503531. It is to be noted that this predetermined value of the integration signal 103 corresponds to a first acceleration as a criterion for a first discrimination means.
Referring to FIG. 5, the output part 15 comprises a resistor 15A and a transistor 15B. Normally, the output indicative signal 104 of the operation decision part 14 is in high level, and the transistor 15B is turned off. When the output indicative signal 104 is output from the operation decision part 14 to put a signal line thereof in low level, the transistor 15B is turned on. Referring to FIG. 6, an auxiliary power supply part 16 steps up in a step-up part 16A a supply voltage 106 of a power supply part which is a battery of the vehicle, and charges a condenser 16D via an anti-counterflow diode 16B and a charging current restrainer resistor 16C. When the transistor 15B of the output part 15 is turned on, electric energy charged in the condenser 16D is supplied to the interior system operation part 3 via a power supply line 105, the transistor 15B, and a power supply line 107. The interior system operation part 3 comprises an electric igniter or squib, and a gas generator for generating, for example, nitrogen gas by actuation of the squib to operate the air bag and the seat belt pretensioner. A mechanical sensor part 17 includes a switch turning on when detecting acceleration greater than a predetermined value and in a predetermined direction, and it operates by smaller acceleration than that one relative to the electronic acceleration sensor part 11. Accordingly, when the mechanical sensor part 17 is operated, current passes from the output part 15 to the ground via the interior system operation part 3 and a power supply line 108, igniting the gas generator by the squib, thus operating the interior system operation part 3.
However, such known controller for an interior system is not designed in view of reutilization thereof, i.e., it should be changed if the interior system operation part is once operated, resulting in increased cost of the controller.
It is, therefore, an object of the present invention to provide a controller for an interior system for an automotive vehicle which can be used repeatedly.